Which of the following layers is NOT a layer of the skin?

The correct answer is that subcutaneous tissue is not considered a layer of the skin. The skin itself is primarily made up of three distinct layers: the epidermis, dermis, and hypodermis.

The epidermis is the outermost layer, providing a protective barrier and containing skin cells, pigments, and other components that contribute to skin health. Beneath the epidermis lies the dermis, which provides structural support, elasticity, and houses important structures such as blood vessels, nerves, hair follicles, and glands. The hypodermis, also known as subcutaneous tissue, lies below the dermis and connects the skin to underlying tissues and organs, serving as an insulating layer and energy reserve.

While the hypodermis can play a role in the overall structure supporting the skin, it is not classified as a layer of the skin itself. Instead, it is essentially a layer of tissue that supports and anchors the skin to underlying structures. Thus, subcutaneous tissue distinguishes itself from the defined layers of the skin: epidermis, dermis, and hypodermis.